The blasts, at just after 09.30 (0730 GMT) on January 31, caused part of the five-storey building in the western Davutpasha district to collapse.

Mayor Kadir Topbas said the first blast sparked a fire that drew onlookers, and minutes later there was a second explosion, which is when most of the victims are thought to have been injured or killed.

A number of people were taken to hospital.

Rescuers working at the scene said there were no further signs of life from beneath the rubble. The authorities have ruled out terrorism as the cause of the blast.

City officials said a fireworks factory had been operating in the building for more than two years without a license.